Thermostat.



No. 643,722. Pat ented Feb. 20, 1900.

C. E. MAY. THERMOSTAT.

(Application filed Nov. 14, 1898.) (lo Iodul.)

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CHARLES EDWARD MAY, OF DUNEDIN, NEW ZEALAND.

TH ERMOSTAT.

SPECIFICATION forming part of Letters Patent No. 643,722, dated February20, 1900.

Application filed November 14, 1898. Serial No. 696,488. (No model.)

To ctZZ whom it may concern:

Be it known that 1, CHARLES EDWARD MAY, of Dunedin, New Zealand, haveinvented certain new and useful Improvements in Thermostats, of whichthe following is a specification.

This invention relates to thermostats for detecting the presence of firein a building and completing an electric circuit when the buildingbecomes unduly heated for the purpose of operating an alarm.

The drawing shows a front view of the thermostat.

B is a metallic wire, which is stretched between two supports N, one ofwhich is preferably provided with some approved means, such as a screwn, for adjusting the tension of the wire to a prearranged degree ofheat, which is not to be exceeded without giving an alarm.

D is a movable contact-piece suspended from the wire B between thesupports N and descending by gravity when the wire is heated.

E is a stationary contact-piece arranged in the downward path of themovable contactpiece. The stationary contact-piece may be set oradjusted vertically in any approved manner, and it preferably consistsof a cup partially filled with mercury.

A are the line-wires of a battery K, and I is an annu'nciator includedin the circuit. One wire A is connected to one of the supports N, andthe other wire A is connected to the contact-piece E.

When a fire occurs in a building supplied with one or more of thesedevices and the heat is so great as to cause the movable con tact-pieceto complete the circuit, an alarm is sounded.

\Vhat I claim is The combination, with a metallic wire, and means forstretching it; of a movable contact-piece suspended from the wirebetween its ends and descending by gravity when the Wire is heated, anda stationary contact-piece arranged in the downward path of the movablecontact-piece, substantially as set forth.

Dated this 4th day of August, 1898.

CHARLES EDWARD MAY.

lVitnesses:

CHARLES MAY, ROBERT LANGTON.

